There exists an immediate need for remediation of contaminated sites thiroughout the world. A sampling of the massive environmental remediation problem in the United States can be seen from a list of contaminated sites/facilities requiring cleanup: Superfund sites, 1,500-2,100; Resource Conservation and Recovery Act (RCRA) action sites, 1,500-3,500; underground storage tanks, 295,000; DOD facilities, 7,300 sites at 1,800 installations; DOE facilities, 4,000 sites at 110 installations; other federal agencies, 350 sites; and, other state agencies, 19,000 sites. A high percentage of the sites require soil remediation; most of them have contaminants in common: solvents, petroleum products, metals, and metal salts. In many cases, different cleanup programs will use similar treatment technologies. At Superfund sites, for example, one of the greatest potential needs for innovative technologies is treatment of ground water in place, without pumping to the surface (pump and treat). At the 500 National Priorty List (NPL) sites, the common contaminants are volatile organic compounds at 60% of the sites, metals at 53%, and semi-volatile compounds at 27%. Given the magnitude of the contamination problem, the development of remediation methodologies that can treat very large quantities of contaminated soil is an important need.
In environmental remediation, it is often desirable to treat soils and groundwater in-situ, due to regulatory, economic, and technical considerations, as opposed to treating through ex-situ methods. Early soil remediation techniques utilized mainly ex-situ methods such as soil washing and incineration. In-situ methods have the advantage of precluding the need for removal and disposal, incineration, or above-ground treatment of the contaminated soil. Over the past decade, in-situ methods have attracted increasing attention because they are likely cost-effective, less hazardous, and minimize disruption to the environment. However, the long time periods required for typical in-situ biorememdiation methods limits the practical utility of these approaches. A comprehensive eight-volume series on innovative site and waste remediation technologies, published by WASTECH, reviews the practical aspects of these and other technologies relevant to the present invention [Anderson, W. C. (Ed.), Innovative Site Remediation Technology--Eight-Volume Series, WASTECH (American Academy of Environmental Engineers), Annapolis, Md., 1994].
Shock waves have been used to initiate chemical reactions in both organic and inorganic compounds [Graham, R. A., Morosin, B., Venturini, E. L. and Carr, M. J., Ann. Rev. Mater. Sci., 16:315 (1986); National Materials Advisory Board, National Research Council, Shock Compression Chemistry in Materials Synthesis and Processing, Publication NMAB-414, National Academy Press, Washington D.C. (1984)]. A well known example of shock induced chemical reaction is the detonation of high explosives [Fickett, W. and Davis, W. C., Detonation, University of California Press, Los Angeles (1979)]. Unlike previous studies on neat materials [National Materials Advisory Board, National Research Council, Shock Compression Chemistry in Materials Synthesis cand Processing, Publication NMAB-414, National Academy Press, Washington D.C. (1984)], the interest for soil remediation involves chemical changes in organic contaminants dispersed in geologic media.
It is a fundamental principle of chemistry that energy must be imparted to a chemical compound in order to change its structure. For in-situ soil remediation, the problem is one of how to transmit energy throughout a contaminated site in a form that is efficient at inducing desirable chemical conversions, i.e. changing toxic chemical compounds into nontoxic ones. Thus, while it is well known that large amplitude shock waves produce profound physiochemical changes in both pure energetic (e.g. detonation of high explosives) and non-energetic materials, there has been no prior showing that shock waves induce chemical changes in chemical contaminants in geological media, e.g., soil. Also, the relationship between the shock loading conditions (e.g., pulse amplitude and duration) and the inducement of chemical changes in compounds dispersed in geologic media has not previously been established.